2014: Back in 1971, Apollo 15 astronauts orbiting the Moon photographed
something very odd. Researchers called it "Ina," and it looked
like the aftermath of a volcanic eruption.
There's nothing odd
about volcanoes on the Moon, per se. Much of the Moon's ancient surface
is covered with hardened lava. The main features of the "Man in the
Moon," in fact, are old basaltic flows deposited billions of years ago
when the Moon was wracked by violent eruptions. The strange thing about Ina was
have long thought that lunar volcanism came to an end about a billion years
ago, and little has changed since. Yet Ina looked remarkably fresh. For more
than 30 years Ina remained a mystery, a "one-off oddity" that no one
Turns out, the mystery
is bigger than anyone imagined. Using NASA's Lunar Reconnaissance Orbiter, a
team of researchers led by Sarah Braden of Arizona State University has found
70 landscapes similar to Ina. They call them "Irregular Mare Patches"
or IMPs for short.
features on the lunar surface was thrilling!" says Braden. "We looked
at hundreds of high-resolution images, and when I found a new IMP it was always
the highlight of my day."
mare patches look so different than more common lunar features like impact
craters, impact melt, and highlands material," she says. "They
really jump out at you."
On the Moon, it is
possible to estimate the age of a landscape by counting its craters. The
Moon is pelted by a slow drizzle of meteoroids that pepper its surface with
impact scars. The older a landscape, the more craters it contains.
Some of the IMPs they
found are very lightly cratered, suggesting that they are no more than 100
million years old. A hundred million years may sound like a long time, but in
geological terms it's just a blink of an eye. The volcanic craters LRO found may
have been erupting during the Cretaceous period on Earth--the heyday of
dinosaurs. Some of the volcanic features may be even younger, 50 million years
old, a time when mammals were replacing dinosaurs as dominant lifeforms.
"This finding is
the kind of science that is literally going to make geologists rewrite the
textbooks about the Moon," says John Keller, LRO project scientist at the
Goddard Space Flight Center.
IMPs are too small to
be seen from Earth, averaging less than a third of a mile (500 meters) across
in their largest dimension. That's why, other than Ina, they haven't been
found before. Nevertheless, they appear to be widespread around the nearside
of the Moon.
"Not only are the
IMPs striking landscapes, but also they tell us something very important about
the thermal evolution of the Moon," says Mark Robinson of Arizona State
University, the principal investigator for LRO's high resolution camera. "The
interior of the Moon is perhaps hotter than previously thought."
"We know so
little of the Moon!" he continues. "The Moon is a large mysterious
world in its own right, and its only three days away! I would love to land on
an IMP and take the Moon's temperature first-hand using a heat probe."
Some people think the
Moon looks dead, "but I never thought so," says Robinson, who won't
rule out the possibility of future eruptions. "To me, it has always been
an inviting place of magnificent beauty, a giant magnet in our sky drawing me
Young volcanoes have
only turned up the heat on the Moon's allure. Says Robinson … "let's
When we look around, everything we can see is made of
matter. For every type of matter from electrons, protons and quarks there is a
similar type of matter known as antimatter. So why aren’t there piles of
antimatter rocks, cars and chocolate bars just lying around? Why does Scotty
always have a little extra kicking around in his liquor cabinet? And where do I
The primary difference between matter and antimatter is
that they have opposite electric charge. Which seems pretty mundane. The
negatively charged electron has an antiparticle known as the positron, which
has a positive electric charge.
Anti-protons have a negative charge, and are just flat
out grumpy. We’ve been able to create these particles in the lab, and have even
been able to create small amounts of anti-hydrogen consisting of a positron
bound to an antiproton, when examined closely there’s were shown to have a
goatee and a little colorful sash or dagger.
When we create particles in accelerators such as the
Large Hadron Collider, we seem to
get equal amounts of matter and antimatter. This suggests that when particles
were formed soon after the big bang, there should have been equal amounts of
matter and antimatter.
But the universe we observe is only made of matter,
and… here’s the best part… we have no idea why. Why didn’t the matter and
antimatter completely annihilate each other? How come we ended up with a little
more matter? This delightful mystery is known as baryon asymmetry.
We do have a few ideas, and by we, I mean some giant
brained crackerjacks have come up with a few plausible options. The most
popular is that somehow antimatter behaves a little differently than matter.
This could cause an imbalance between matter and antimatter. After particles
collided in the early universe, there would still be matter left over, hence
the matter we observe.
Another idea is that the observable universe just
happens to be in a region dominated by matter. Other parts of the multiverse could have observable
universes dominated by antimatter. Baryon asymmetry is one of the big mysteries
of modern cosmology.
There is an even crazier idea. Antimatter might have
anti-gravity. In other words, an atom of anti-hydrogen would fall up instead of
down. If that is the case, then matter and antimatter would repel each other,
and you might have matter universes and antimatter universes that are forever separate.There have been some
initial experiments to test this idea, but so far there have been no conclusive
What do you think? Where’s all our antimatter and how
do we track it down? I’d sure love to bring some home and show my friends
(Phys.org) —The giant black hole at the center of the
Milky Way may be producing mysterious particles called neutrinos. If confirmed,
this would be the first time that scientists have traced neutrinos back to a
The evidence for this came from three NASA satellites
that observe in X-ray light: the Chandra X-ray Observatory, the Swift gamma-ray
mission, and the Nuclear Spectroscopic Telescope Array (NuSTAR).
Neutrinos are tiny particles that carry no
charge and interact very weakly with electrons and protons. Unlike light
particles, neutrinos can emerge from
deep within their cosmic sources and travel across the universe without being
absorbed by intervening matter or, in the case of charged particles, deflected
by magnetic fields.
The Earth is constantly bombarded with neutrinos from
the sun. However, neutrinos from beyond the solar system can be millions or
billions of times more energetic. Scientists have long been searching for the
origin of ultra-high energy and very high-energy neutrinos.
"Figuring out where high-energy neutrinos come
from is one of the biggest problems in astrophysics today," said Yang Bai of the University of
Wisconsin in Madison, who co-authored a study about these results published
Review D. "We now have
the first evidence that an astronomical source – the Milky Way's supermassive black hole – may be
producing these very energetic neutrinos."
Because neutrinos pass through material very easily, it
is extremely difficult to build detectors that reveal exactly where the
neutrino came from. The IceCube Neutrino Observatory,
located under the South Pole, has detected 36 high-energy neutrinos since the
facility became operational in 2010.
By pairing IceCube's capabilities with the data from the three X-ray
telescopes, scientists were able to look for violent events in space that
corresponded with the arrival of a high-energy neutrino here on Earth.
"We checked to see what happened after Chandra
witnessed the biggest outburst ever detected from Sagittarius A*, the Milky
Way's supermassive black hole,"
said co-author Andrea Peterson, also of the University of Wisconsin. "And
less than three hours later, there was a neutrino detection at IceCube."
In addition, several neutrino detections appeared
within a few days of flares from the supermassive black hole that were observed with Swift and NuSTAR.
"It would be a very big deal if we find out that
Sagittarius A* produces neutrinos," said co-author Amy Barger of the
University of Wisconsin. "It's a very promising lead for scientists to
Scientists think that the highest energy neutrinos were created in
the most powerful events in the Universe like galaxy mergers, material falling
onto supermassiveblack holes, and the winds around
dense rotating stars called pulsars.
The team of researchers is still trying to develop a
case for how Sagittarius A* might produce neutrinos. One idea is that it could
happen when particles around the black hole are accelerated by a shock wave,
like a sonic boom, that produces charged particles that decay to neutrinos.
This latest result may also contribute to the
understanding of another major puzzle in astrophysics: the source of
high-energy cosmic rays. Since the charged particles that make up cosmic rays
are deflected by magnetic fields in our Galaxy, scientists have been unable to
pinpoint their origin. The charged particles accelerated by a shock wave near Sgr A* may be a
significant source of very energetic cosmic rays.
Scientists have proven
that a technique for accelerating particles on waves of plasma is efficient
enough to power a new generation of shorter, more economical particle
Using the Facility for
Advanced Accelerator Experimental Tests (FACET) at SLAC National Accelerator
Laboratory, scientists from SLAC and the University of California, Los Angeles,
boosted bunches of electrons to energies 400 to 500 times higher than they
could have reached traveling the same distance in a conventional accelerator.
They were able to transfer energy to the electrons with an unprecedented level
described in Nature, could eventually lead to an expansion in the use of plasma
wakefield acceleration in areas
such as medicine, national security, industry and high-energy physics research.
“Many of the practical
aspects of an accelerator are determined by how quickly the particles can be
accelerated,” says SLAC accelerator physicist Mike Litos, lead author of the
paper. “To put these results in context, we have now shown that we could use
this technique to accelerate an electron beam to the same energies achieved in
the 2-mile-long SLAC linear accelerator, in less than 20 feet.”
Plasma wakefields have been of interest
to accelerator physicists for 35 years as one of the more promising ways to
drive the smaller, cheaper accelerators of the future. The UCLA and SLAC groups
have been at the forefront of research on plasma wakefield acceleration for more than a decade.
In this experiment,
researchers sent pairs of electron bunches containing 5 billion to 6 billion
electrons each into a laser-generated column of plasma inside an oven of hot
lithium gas. The first bunch in each pair blasted all the free electrons away
from the lithium atoms, leaving the positively charged lithium nuclei behind—a
configuration known as the “blowout regime.” The blasted electrons then fell
back in behind the second bunch of electrons, forming a “plasma wake” that
propelled the trailing bunch to higher energy.
had demonstrated multi-bunch acceleration, but the team at SLAC was the first
to reach the high energies of the blowout regime, where maximum energy gains at
maximum efficiencies can be found. Of equal importance, the accelerated electrons
wound up with a relatively small energy spread.
“These results have an
additional significance beyond a successful experiment,” says Mark Hogan, SLAC
accelerator physicist and one of the principal investigators of the experiment.
It “has enabled us to increase the acceleration efficiency to a maximum of 50
percent—high enough to really show that plasma wakefield acceleration is a viable technology for future
The plasma source used
in the experiment was developed by a team of scientists led by Chandrashekhar Joshi, director of
the Neptune Facility for Advanced Accelerator Research at UCLA.
“It is gratifying to
see that the UCLA-SLAC collaboration on plasma wakefield acceleration continues to solve seemingly intractable
problems one by one through systematic experimental work,” Joshi says. “It is
this kind of transformative research that attracts the best and the brightest
students to this field, and it is imperative that they have facilities such as
FACET to carry it out.”
There are more
milestones ahead. Before plasma wakefield acceleration can be put to use, Hogan says, the
trailing bunches must be shaped and spaced just right so all the electrons in a
bunch receive exactly the same boost in energy, while maintaining the high
overall quality of the electron beam.
“We have our work cut
out for us,” Hogan says. “But you don’t get many chances to conduct research
that you know in advance has the potential to be immensely rewarding, both
scientifically and practically.”
used in the experiments were developed by Warren Mori’s group at UCLA.
Additional contributors included researchers from SLAC, the University of Oslo
in Norway, Tsinghua University in China
and Max Planck Institute for Physics in Germany. The research was funded by the
DOE Office of Science.
(Phys.org) —The same phenomenon that causes a bumpy
airplane ride, turbulence, may be the solution to a long-standing mystery about
stars' birth, or the absence of it, according to a new study using data from
NASA's Chandra X-ray Observatory.
Galaxy clusters are the largest objects in the
universe, held together by gravity. These behemoths contain hundreds or
thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees.
This hot gas, which is the heftiest component of
from unseen dark matter, glows brightly in X-ray light detected by Chandra.
Over time, the gas in the centers of these clusters should cool enough that
stars form at prodigious rates. However, this is not what astronomers have
observed in many galaxy clusters.
"We knew that somehow the gas in clusters is being
heated to prevent it cooling and forming stars. The question was exactly
how," said Irina Zhuravleva of Stanford
University in Palo Alto, California, who led the study that appears in the
latest online issue of the journal Nature. "We think we may have found evidence
that the heat is channeled from turbulent motions, which we identify from
signatures recorded in X-ray images."
Prior studies show supermassive black holes, centered in large
galaxies in the middle of galaxy clusters, pump vast quantities of energy
around them in powerful jets of energetic particles that create cavities in the hot gas.
Chandra, and other X-ray telescopes, have detected these giant cavities before.
The latest research by Zhuravleva and her colleagues provides new insight into how
energy can be transferred from these cavities to the surrounding gas. The
interaction of the cavities with the gas may be generating turbulence, or
chaotic motion, which then disperses to keep the gas hot for billions of years.
"Any gas motions from the turbulence will
eventually decay, releasing their energy to the gas," said co-author
Eugene Churazov of the Max Planck
Institute for Astrophysics in Munich, Germany. "But the gas won't cool if
turbulence is strong enough and generated often enough."
The evidence for turbulence comes from Chandra data on
two enormous galaxy clusters named Perseus and Virgo. By analyzing extended observation data of
each cluster, the team was able to measure fluctuations in the density of the
gas. This information allowed them to estimate the amount of turbulence in the
"Our work gives us an estimate of how much
turbulence is generated in these clusters," said Alexander Schekochihin of the University of
Oxford in the United Kingdom. "From what we've determined so far, there's
enough turbulence to balance the cooling of the gas.
These results support the "feedback" model
involving supermassive black holes in the
centers of galaxy clusters. Gas cools and falls toward the black hole at an
accelerating rate, causing the black hole to increase the output of its jets,
which produce cavities and drive the turbulence in the gas. This turbulence
eventually dissipates and heats the gas.
While a merger between
two galaxy clusters may also produce turbulence, the researchers
think that outbursts from supermassiveblack holes are the main
source of this cosmic commotion in the dense centers of many clusters
Astronomers have confirmed that ice exists on one of
the least likely places in the solar system—Mercury.
The planet is among the solar system’s hottest—only
Venus has higher average temperatures—thanks to the sun’s searing proximity,
which raises temperatures to as high as 800˚ F. But hidden in the frigid
shadows—where temperatures can sink as low as -280˚ F—are frozen patches that
are the likely remains of icy comets which have blasted the rocky terrain over
the last 100 million years.
Scientists have long suspected that Mercury is home to solid H2O,
but recent photos taken by the MESSENGER probe confirm it. Here’s Michael Lemonick, reporting for Time:
These are the first optical images, and nobody is
entirely sure how the ice got there. One idea is that it was released from
water-bearing rock in Mercury’s crust. But the leading theory suggests it
arrived instead in the form of impacts from icy comets, which may well be the
same way Earth got its oceans. “It’s a fair amount of ice,” Chabot said, “about
equivalent to the water in Lake Ontario, so if it was one comet, it was a
pretty sizable one.” More likely, she said, it would have been a series of smaller
comets, falling over billions of years.
Mercury’s extreme temperature fluctuations are thanks to its
extremely thin atmosphere. The planet’s small mass means it has a hard time
holding onto gas particles, and the sun’s intense rays do their best to blast
away what little that does cling to the rocky world. If the planet had a denser
atmosphere, it would more closely resemble Venus, where the thick sky keeps
average temperatures above 860˚ F.
Mercury’s thin atmosphere gives scientists another
unique opportunity. Next spring, MESSENGER will be able to fly just 12 miles
above the surface without burning up. During that pass, it will take
extraordinarily high-resolution images of the planet, giving scientists a
unique window into a world of extremes.
Here’s one reason libraries hang on to old science
journals: A paper from an experiment conducted 32 years ago may shed light on
the nature ofdark
matter, the mysterious stuff
whose gravity appears to keep the galaxies from flying apart. The old data put
a crimp in the newfangled concept of a "dark photon" and suggest that
a simple bargain-basement experiment could put the idea to the test.
No one really knows what dark matter is. Since the
1980s, theorists' best hunch has been that it consists of so-called weakly
interacting massive particles, or WIMPs. If they exist, WIMPs would have a mass
between one and 1000 times that of a proton. They would interact only through
the feeble weak nuclear force—one of two forces of nature that ordinarily flex
their muscle only within the atomic nucleus—and could disappear only by
colliding and annihilating one another. So if the infant universe cooked up
lots of WIMPs, enough of them would naturally survive to produce the right
amount of dark matter today. But physicists
have yet to spot WIMPs, which every now and then should ping off atomic
nuclei in sensitive detectors and send them flying.
More recently, theorists have explored other ideas,
such as self-interacting dark matter. This would consist of a particle, known
as a χ (pronounced chi), with a mass between 1/1000 and one times that of the
proton. Those particles would interact with one another through a force like
the electromagnetic force, which produces light. That force would be conveyed
by a massive particle called a dark photon—a dark matter version of a particle
of light—that might "mix" slightly with the ordinary ones. So with
some small probability, a dark photon might interact with ordinary charged
particles such as electrons and atomic nuclei—just as ordinary photons do.
Self-interacting dark matter has attractive properties.
In particular, a dark photon could also explain a particle physics puzzle. A
particle called the muon appears to be very
slightly more magnetic than theory predicts, and that discrepancy could be
resolved if the muon interacts with dark
photons lurking in the vacuum. However, χs and dark photons would be hard to detect with WIMP
detectors; with their low masses, they couldn't whack a nucleus hard enough to
create a signal.
But archival data already rule out dark photons with
certain combinations of properties, argues RouvenEssig, a theoretical
physicist at Stony Brook University in New York, and his colleagues. The data
come from E137, a "beam dump" experiment that ran from 1980 to 1982
at SLAC National Accelerator Laboratory in Menlo Park, California. In the
experiment, physicists slammed a beam of high-energy electrons, left over from
other experiments, into an aluminum target to see what would come out.
Researchers placed a detector 383 meters behind the target, on the other side
of a sandstone hill 179 meters thick that blocked any ordinary particles. They
then looked for hypothetical particles called axions, which would have pierced the earth and reached the
detector—and saw none.
But electrons hitting the target should also have
produced a beam of high-energy χs. A χ could have traversed the hill and interacted with
an electron in the detector through a dark photon, blasting it into motion. The
fact that E137 saw no recoiling electrons enabled Essig and his colleagues
some possible combinations of the dark photon's mass and the strength of its
mixing with ordinary
photons, as they report this week in Physical Review Letters. The results do not
prove that the dark photon cannot exist at all, but they do put limits on its
Other physicists have used archival data to test new
dark matter theories. Last year, Philip Schuster, a theorist at the Perimeter
Institute for Theoretical Physics in Waterloo, Canada, and a colleague used the
result from another beam dump experiment at SLAC that ran in 1994 and 1995 to
probe self-interacting dark matter. But the millicharge, or mQ, experiment was sensitive to χs sending atomic nuclei
flying and set somewhat looser limits. "The electron-recoil limit looks a
little better," Schuster says.
With certain assumptions, the analysis disfavors a dark
photon with the properties needed to explain the muon's magnetism. But those assumptions could be loosened and
the idea more thoroughly tested with a new experiment, Schuster says. He and
roughly 80 other physicists hope to build a new beam dump experiment called
BDX, which would look at 100 times as many events as E137 did. They have
submitted a letter of intent to the Thomas Jefferson National Accelerator
Facility in Newport News, Virginia, although the experiment could be staged
Compared with some particle physics experiments, BDX
would be small and cheap, says Marco Battaglieri of Italy's National Institute for Nuclear Physics in
Genoa and co-spokesman for the BDX team. "We are not talking about
thousands of tons of detector," he says. "We are talking about a
1-ton detector." BDX would cost a few million dollars, Battaglieri says.
The study also suggests it's not so easy to dream up
models of dark matter that don't run afoul of data already taken, Schuster
says: "All of this has to be done in a very tight straitjacket."
are hoping to hit pay dirt with a proposed experiment—the first of its kind in
the Southern Hemisphere—that would search for traces of dark matter more than a
half mile below ground in Victoria, Australia.
current plan, now being explored by an international team, is for two new,
identical dark matter experiments to be installed and operated in parallel—one
at an underground site at Grand Sasso National Laboratory in Italy, and the
other at the Stawell Gold Mine in Australia.
experiment of this significance could ultimately lead to the discovery of dark
matter,” says ElisabettaBarberio of the ARC Centre of Excellence for
Particle Physics at the Terascale (CoEPP) and the University of Melbourne, who
is Australian project leader for the proposed experiment.
experiment proposal was discussed during a two-day workshop on dark matter in
September. Work could begin on the project as soon as 2015 if it gathers enough
support. “We’re looking at logistics and funding sources,” Barberio
experiments would be modeled after the DAMA experiment at Gran Sasso,
now called DAMA/LIBRA, which in 1998 found a possible sign of dark matter.
looks for seasonal modulation, an ebb and flow in the amount of potential dark
matter signals it sees depending on the time of year.
the Milky Way is surrounded by a halo of dark matter particles, then the sun is
constantly moving through it, as is the Earth. The Earth’s rotation around the
sun causes the two to spend half of the year moving in the same direction and
the other half moving in opposite directions. During the six months in which
the Earth and sun are cooperating, a dark matter detector on the Earth will
move faster through the dark matter particles, giving it more opportunities to
seasonal difference appears in the data from DAMA/LIBRA, but no other
experiment has been able to confirm this as a sign of dark matter.
one thing, the changes in the signal could be caused on other factors that
change by the season.
are environmental effects—different characteristics of the atmosphere—in winter
and summer that are clearly reversed if you go from the Northern to the
Southern hemisphere,” says Antonio Masiero, vice president for the Italian
National Institute of Nuclear Physics (INFN) and a member of the Italian
delegation collaborating on the proposal, which also includes Gran Sasso
Director Stefano Ragazzi. If the results matched up at both sites at the same time of
year, that would help to rule out such effects.
Australian mine hosting the proposed experiment could also house scientific
experiments from different fields.
wouldn’t be limited to particle physics and could include experiments involving
biology, geosciences and engineering,” Barberio says. “These could include neutrino
detection, nuclear astrophysics, geothermal energy extraction and carbon
sequestration, and subsurface imaging and sensing.”
testing has begun at the mine site down to depths of about 880 meters, about
200 meters above the proposed experimental site. Regular mining operations are
scheduled to cease at Stawell in the next few years.
ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), the local
government in the Victoria area, and the mine operators have joined forces with
COEPP and INFN to support the proposal.